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Solutions For Lateral Rehab
“For a 60-foot pipebursting lateral installation, about 45 feet will be trenchless with excavations necessary at each end,” said Chris Brahler, president of TT Technologies, a leading manufacturer of pipebursting equipment and technology.
Compact bursting equipment and tools have been developed specifically for sewer laterals. Brahler said there are two basic types of bursting methods for laterals: pneumatic and static.
“The pneumatic method employs a pneumatic piercing tool as the bursting device,” he explained. “An entry pit is dug and the tool inserted in the old pipe with new pipe attached to the rear with the air hose enclosed in the new pipe. The hammering action is activated and a small lateral winch pulls the tool through the old pipe to the exit pit. Once in place the new lateral pipe is connected at the property end and to the sewer main.”
This method is best suited for straight runs, said Brahler.
Static (also called hydraulic) bursting is preferred for laterals with bends and curves. This method’s shorter bursting tools can better negotiate changes in direction than longer piercing tools.
The TT Technologies Grundotugger static pipebursting system includes a hydraulic winch unit, bursting heads for various sizes and types of pipes, and cable to connect to tool and winch. A 20-horsepower gasoline power pack and extraction cage also are available. To make a burst, the winch unit is placed in the exit pit, and then cable is passed through the old pipe and connected to the bursting head. With new pipe attached to the rear of the head, it is pulled through the pipe by the winch, busting old pipe and pulling in new pipe. When new pipe is in place, connections are made at each end.
“Entry and exit pits are the most time consuming of a bursting project,” said Brahler. “For pneumatic jobs, the entry pit is the largest to accommodate the length of the piercing tool. It’s just the opposite with hydraulic equipment because the exit pit holds the winch.”
Because pneumatic jobs are straight, they take less time to complete.
“A straight shot of 50 feet or less with a pneumatic tool can be completed in an hour or less,” he said. “A lateral the same length with bends could take two to four hours with static equipment. There’s more set up time, and the pipe pull-through is slower.”
For difficult straight static installations, a pneumatic piercing tool can be placed inside of the product pipe behind the expander to provide a percussive assist during a lateral burst.